Technical Field
The present invention relates to a monitoring apparatus mounted in an own vehicle and a non-transitory computer-readable medium.
Background Art
Conventionally, a driving assistance technique is known for detecting an object, such as a vehicle traveling around an own vehicle or a roadside wall or the like, with use of a laser radar, a camera or the like, and based on the detection result, providing driving assistance. However, an airborne substance, such as mist present on a roadway or an exhaust gas from a preceding vehicle or the like, that is not an obstacle a driver usually attempts to avoid, may be detected as an object, which may prevent proper driving assistance.
An object detection apparatus disclosed in Patent Literature 1 uses a sensor, such as a stereoscopic camera or the like, to measure a distance to an object located forward of the own vehicle on a pixel block-by-pixel block basis, where the pixel blocks are laterally arranged in-line. Based on the measured distances, the apparatus, in a top plan view of the own vehicle, plots a point to an object position for each pixel block and groups adjacent points to thereby detect individual objects, and for each object, calculates an average deviation of distances to the corresponding points and an average of absolute values of differences between distances to the adjacent points (average distance difference). Finally, if the average deviation and the average distance difference exceed respective predetermined thresholds, the apparatus determines that the object as being an airborne substance because of its high variation of the distances to the points corresponding the object.
Technical Problem
The applicants have identified that, as shown in FIG. 9, for example, in a configuration where a probe wave is irradiated to a search range having a width in a widthwise direction of the own vehicle increasing in the forward direction (going away direction) from the centered front end of the own vehicle to scan the search range, and in each direction a distance to a corresponding point is measured, the variation of the distances to the points corresponding to the object varies with distances from the own vehicle to the object even if the object is located at different distances from the own vehicle with the same orientation. More specifically, the variation of the distances to the points corresponding to the object increases with increasing distance from the own vehicle. That is, the variation of the distances to the points corresponding to the object decreases with decreasing distance from the own vehicle.
In contrast, in the object detection apparatus disclosed in Patent Literature 1, a threshold used to determine the presence or absence of an airborne substance takes a fixed value. Therefore, for example, even if an object located close to the own vehicle is an airborne substance, a measure of variation, such as the average deviation or the average distance difference, may be below the threshold and the object thus may be incorrectly determined as a non-airborne substance (that is, an obstacle). Thus, there is a problem that if the driving assistance apparatus of the own vehicle determines the airborne substance as an obstacle and then activates the automatic brake in providing collision avoidance control, and travel of a following vehicle may be unnecessarily affected.